Parents voiced concerns Monday night that three proposals for changing the way their children are assigned to schools in Boston could limit families’ access to a good education, and they asked a special panel to delay a key vote on the matter scheduled for Saturday.

“We feel there are promises; we haven’t seen a plan how they will be fulfilled,” said Samuel Hurtado, the father of a student at the Josiah Quincy School in Chinatown. “So please postpone the vote. We need more time.”

Hurtado, one of the approximately 250 people attending the meeting at the Orchard Gardens K-8 school in Roxbury to discuss the proposals, was refer­ring to a vote by the External Advisory Committee set for Saturday. That panel was ­appointed by Mayor Thomas M. Menino to select the best plan to recommend to the School Committee.

The committee took no ­action on the request.

Another parent, Randi ­Bonilla of Dorchester, said during the public comment period that she has struggled to get both of her children into the same high-performing school that only one of them currently attends. And, she said, she is unsure how any of the plans under consideration will improve her situation.

“I have one child who goes to a quote, good school, and the other one that goes to a not so good school,” Bonilla said. “The not so good school is around the corner from my house. But I take the time every morning, leaving the house at 6:30 in the morning, to get my baby to the good school. I want to give both of my children the same kind of education.”

Bonilla said her children ­attend the Orchard Gardens school and the Martin Luther King Jr. school in Dorchester.

Late last month, school officials released three plans after parents and advocates criticized previous proposals, which they said would leave too many students with only the option of low-achieving schools.

One of the three plans currently on the table would create 10 assignment zones that ­divide the city’s approximately 80 elementary and K-8 schools and its early childhood centers, a proposal that would offer ­between three and 14 school choices.

The two other proposals, created with assistance from an MIT doctoral student and a professor, call for no zones.

Instead, a complex algorithm would generate a list of schools that parents can choose from based on a variety of factors, such as distance from home, school capacity, and MCAS performance. One of the “no-zone” proposals would guarantee at least six school choices and the other at least nine.

Changing the school assignment system is a priority for Menino, who believes that having more children who live on the same streets attending the same schools would improve the fabric of neighborhoods.

The new plan is scheduled to take effect in September 2014. Students currently enrolled in the system will be able to ­remain at their current school even if it does not lie in their new zone, and their younger siblings will be able to select those schools as well.

However, parents at Monday’s meeting repeatedly ­implored school officials, often to applause, to focus on improving school quality before changing the assignment structure.

Superintendent Carol R. Johnson said during brief ­remarks that her staff is working diligently to improve quality across the school district, and those efforts will continue.

“We promise that we’ll continue to work with you,” said Johnson.

James Vaznis of the Globe staff contributed to this report. ­Travis Andersen can be reached at tandersen@globe.com. Follow him on Twitter @TAGlobe.

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